Isotopes radioisotope tagging

Laurence s cyclotron had manufactured many other radioisotopes, but this factory was a very slow and inefficient one compared with a nuclear furnace. With the invention of the nuclear reactor several hundreds of brand new atomic species or isotopes were created for the first time and made available to scores of research centers. The radioactive isotope turned out to be a new, revolutionary, and extremely delicate tool in scientific research. It is used in the so-called tracer or tagged-atom technique. For example, radioactive sodium-24 is substituted for the normal sodium-23 atoms in a bit of... 

Numerous trace elements are known to be nutritionally essential in man In order to assess the essentiality, dietary availability, and metabolic fate of these, means of labeling for subsequent identification are needed In animal studies, radioisotopes are often used for this purpose, but their use in human studies is generally contraindicated due to the radiation hazards An alternate method is to use stable isotopes of the elements, which overcomes this limitation A method will be described for conveniently measuring the stable isotopes of selenium, permitting their use as metabolic tags in tracer studies Using one stable isotope as the tracer and another as internal standard, one can quantitatively identify in a sample the tracer, natural (unenriched) selenium present with it, and total selenium Some of the kinds of information obtainable from metabolic tracer studies will be discussed ... 

Radioisotopes used as tracers solve scientific mysteries Radioactive and nonradioactive isotopes of the same element act the same way in a chemical reaction. When scientists want to put tags on a compound, they substitute a radioactive isotope for a nonradioactive one in the compound. Then they can use radiation detectors to track and locate the radioisotope tracer. 

While the radioisotopic labelling method described above has some tmquestionable advantages, the fluorescence labelling method has its outstanding features as well the sensitivity of quantitative assays is at least comparable with isotopic methods. An amount of about 10 ng of polymer tagged with one mole of fluorochrome per thousand moles of monomer units can be quantitatively determined in biological... 

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